Sorry but am I the only one wondering why would anyone want only a seat wobbling around? Would you like to drive a car without the seat being bolted? I just can't see the point paying for such thing when it only creates unrealism
Speaking only of my own experience with 2DOF G-Force simulation and 3DOF Seat movers and 3DOF seat/wheel/pedal movers (I have no practical experience of whole rig inc screen movers aside from a ride in a space shuttle simulation) I think it's about what works for you individually - space, immersion and cost... and how practical what you are looking at is for you as an individual needs.
Personally, I cannot afford nor have the space or even the desire to for something that spins me, the wheel/pedals and the monitors around in space.
Originally I was after a 3DOF rig after having the luxury over 3 days with one on my stand at a show a few years ago (lots of after hours racing with my team went on I can tell you). I got motion sickness after extended use and a bit of whiplash too, but it was like a fairground ride in front of a 24" triple screen setup that did not move and I found it hard to get over that, despite thinking "I must have one of these!" for a couple of years...
The Geko fitted my requirements when I got it and completely changed my views completely on wanting a rig that moved my wheel/pedals and I'm a complete convert to g-force s[t]imulation.
I found some space to get a proper racing rig in August and the Geko no longer was a practical solution... I wanted something more racey... but I loved the silence of the Geko and the way g-force simulation fools your brain and decided that I did not want the motion sickness of a rig mover and that 2DOF was good enough for me having had a bash at Codies HQ on a D-Box setup.
So here I am! As I say, it's personal choice and immersion, if it makes you unhappy, then no-one is forcing anyone to agree.